Tunnel entrance elevation specifying device, method for specifying tunnel entrance elevation, computer program for specifying tunnel entrance elevation, and storage medium that stores computer program

Abstract

Systems for automatically specifying a tunnel entrance and methods that accomplish same. One method includes a target entrance selecting step for selecting, from a map data storing portion, a target entrance for specifying an entrance elevation of a tunnel, a target road link assigning step for assigning, from the map data storing portion, a road link, which includes the target entrance, as a target road link, a corrected point extracting step for extracting a certain point as a corrected point, the certain point being located along the target road link and away from the target entrance outwardly of the tunnel by a predetermined distance, a corrected point elevation specifying step for specifying an elevation of the corrected point as a corrected point elevation, and a first target entrance elevation specifying step for specifying the corrected point elevation as a first elevation of the target entrance.

The invention claimed is: 
     
       1. A tunnel entrance elevation specifying device comprising:
 a target entrance selecting portion that selects, from a map data storing portion, a target entrance for specifying an entrance elevation of a tunnel; 
 a target road link assigning portion that assigns, from the map data storing portion, a road link, which includes the target entrance, as a target road link; 
 a corrected point extracting portion that extracts a certain point as a corrected point, the certain point located along the target road link and away from the target entrance outwardly of the tunnel by a predetermined distance; 
 a corrected point elevation specifying portion that specifies an elevation of the corrected point as a corrected point elevation; and 
 a first target entrance elevation specifying portion that specifies the corrected point elevation as a first elevation of the target entrance, wherein the corrected point elevation specifying portion specifies the corrected point elevation based on mesh elevation data that indicates an elevation of a point on a map, the point on the map corresponding to a grid intersection point of a predetermined size mesh. 
 
     
     
       2. The tunnel entrance elevation specifying device according to  claim 1 , comprising:
 a second target entrance elevation specifying portion that specifies a second elevation of the target entrance based on the mesh elevation data; 
 an elevation difference computing portion that computes an elevation difference between the first elevation and the second elevation; and 
 a flag setting portion that sets a flag when the elevation difference is equal to or greater than a predetermined threshold value. 
 
     
     
       3. The tunnel entrance elevation specifying device according to  claim 1 , wherein the predetermined distance is set based on a preassigned condition. 
     
     
       4. A tunnel entrance elevation specifying method comprising:
 a target entrance selecting step for selecting, from a map data storing portion, a target entrance for specifying an entrance elevation of a tunnel; 
 a target road link assigning step for assigning, from the map data storing portion, a road link, which includes the target entrance, as a target road link; 
 a corrected point extracting step for extracting a certain point as a corrected point, the certain point located along the target road link and away from the target entrance outwardly of the tunnel by a predetermined distance; 
 a corrected point elevation specifying step for specifying an elevation of the corrected point as a corrected point elevation; and 
 a first target entrance elevation specifying step for specifying the corrected point elevation as a first elevation of the target entrance, wherein the corrected point elevation specifying step specifies the corrected point elevation based on mesh elevation data that indicates an elevation of a point on a map, the point on the map corresponding to a grid intersection point of a predetermined size mesh. 
 
     
     
       5. The tunnel entrance elevation specifying method according to  claim 4 , comprising:
 a second target entrance elevation specifying step for specifying a second elevation of the target entrance based on the mesh elevation data; 
 an elevation difference computing step for computing an elevation difference between the first elevation and the second elevation; and 
 a flag setting step for setting a flag when the elevation difference is equal to or greater than a predetermined threshold value. 
 
     
     
       6. The tunnel entrance elevation specifying method according to  claim 4 , wherein the predetermined distance is set based on a preassigned condition. 
     
     
       7. A non-transitory computer readable storage medium for specifying a tunnel entrance elevation, the computer readable storage medium containing computer readable code causing a computer to function as:
 target entrance selecting means for selecting, from a map data storing portion, a target entrance for specifying an entrance elevation of a tunnel; 
 target road link assigning means for assigning, from the map data storing portion, a road link, which includes the target entrance, as a target road link; 
 corrected point extracting means for extracting a certain point as a corrected point, the certain point located along the target road link and away from the target entrance outwardly of the tunnel by a predetermined distance; 
 corrected point elevation specifying means for specifying an elevation of the corrected point as a corrected point elevation; 
 first target entrance elevation specifying means for specifying the corrected point elevation as a first elevation of the target entrance, wherein the corrected point elevation specifying means specifies the corrected point elevation based on mesh elevation data that indicates an elevation of a point on a map, the point on the map corresponding to a grid intersection point of a predetermined size mesh. 
 
     
     
       8. The non-transitory computer readable storage medium according to  claim 7 , further causing the computer to function as:
 second target entrance elevation specifying means for specifying a second elevation of the target entrance based on the mesh elevation data; 
 elevation difference computing means for computing an elevation difference between the first elevation and the second elevation; and 
 flag setting means for setting a flag when the elevation difference is equal to or greater than a predetermined threshold value. 
 
     
     
       9. The non-transitory computer readable storage medium according to  claim 7 , wherein the predetermined distance is set based on a preassigned condition.